Electrical load centers of the type adapted to be mounted in a hollow wall structure, comprising a generally rectangular metallic enclosure box and an enclosure cover, are in common use in most residential and some commercial buildings. A prior art load center 2 is shown installed in a hollow wall structure 12 in FIG. 1.
The hollow wall structure 12 comprises, generally, a plurality of vertically disposed studs 14 and a wall panel 16 attached to the studs by fasteners 18. A common wall panel 16 is gypsum "drywall" which is nailed or screwed to the studs 14. Established building practice and many building codes require standard spacing between wall studs, typically sixteen inches center-to-center.
The prior art electrical load center 2 includes an enclosure box 3 and an enclosure cover 4. The enclosure box 3 is mounted between a pair of adjacent studs 14. A high voltage/high current service wire, SW, originating at a utility pole or underground distribution service, is terminated at the load center 2 and is electrically connected to a circuit distribution assembly CD. Lower voltage/current circuit wires CW are electrically connected to the circuit distribution assembly CD and extend from the enclosure box 3. The service wire SW and the circuit wires CW extend through an enclosure sidewall 5 through sidewall apertures 6, commonly referred to as "knock-out" apertures. The service and circuit wires, SW and CW, respectively, are secured against movement by wire clamps 7 that are inserted in the sidewall apertures 6 and secured to the sidewall 5.
During new building construction, all electrical wiring is installed and connected at the load center 2 before the wall panel 16 is installed. Then, the wall panel 16 is installed adjacent the load center box 3 by providing a wall panel cut-out 8 having dimensions only slightly greater, approximately 1/8-1/4 inch, than the outside dimensions of the enclosure box 3. Because the clearances between the edges of the cutout 8 and the enclosure box 3 are so narrow, there is substantially no access to exterior surfaces of the enclosure box, such as the exterior surface of the upper and lower sidewalls 5, after the wall panel 16 has been installed.
After the wall panel 16 is installed, the cover 4 is installed by attaching it with screws to the enclosure box 3. The cover 4 is sized and configured so that it overlays slightly the wall panel 16 adjacent the edges of the cut-out 8 to give a neat appearance.
When new facilities, which require electrical service that exceeds the capacity of the installed electrical circuit cable, are installed in an existing building, it becomes necessary to "pull in" new electrical wiring to provide electrical service to the new facilities. This requires installing electrical circuit wire CW from the electrical load center 2 to the new facility. The installation of new circuit wire CW into the load center enclosure box 3 is complicated because the exterior of the enclosure box is no longer accessible after the wall panel 16 is installed. Electrical codes require that cable clamps 7 be installed in spare sidewall apertures 6 and new wire passed through and secured by the cable clamps. It is difficult, if not impossible, to install a new cable clamp 7 because part of the cable clamp must be installed from the exterior sidewall surface which is not accessible because of the close fit of the wall panel 16 about the enclosure box 3. Also, it is difficult to insert the end of the new circuit wire CW, now positioned within the hollow wall structure behind the wall panel 16, through the cable clamp 7 installed in the sidewall aperture 6 because of the inaccessibility of the wire end. This condition may require the electrician to "fish" for the circuit wire cable end with a special tool from inside the enclosure box 3.
To overcome these problems associated with installing new wiring in an existing building, electricians will oftentimes break away portions of the wall panel 16 adjacent the enclosure box 3 edge to provide access to the external sidewall surfaces of the enclosure box. This allows the electrician to install a new cable clamp 7 and to insert the end of the new circuit wire CW through the new wire clamp. Because the wall panel has been damaged by the procedure, repair of the wall panel is necessitated. Alternatively, the installer may simply avoid installing the wire clamp 7 and secure the new circuit wire CW by other means within the enclosure, or leave the new circuit wire CW unsecured.
Accordingly, there is a need for a means for providing access to external sidewall surfaces of load center enclosure boxes to facilitate the installation of electrical cable into an installed load center enclosure surrounded by a wall panel without removing any portions of the wall panel or damaging the wall panel.